indexoutofboundsexception - Array index out of bounds in sieve of eratosthenes -

i having trouble arrayindexoutofbounds. new coding , don't understand problem , unable fix it. appreciated.

public class primes {  public static void main(string[] args) {  final int size = 10000;         boolean[] numberisprime = new  boolean[size];         int rowcounter = 0;          for( int index = 1; index <= size; index++) {              numberisprime[index] = true;         }          for( int index = 2; index <= size; index++) {              if( numberisprime[index] = true){              for( int = index; <= size; i++){                  numberisprime[index * i] = false;             }         }     }     for( int index = 1; index <= size; index++){         if( numberisprime[index] = true){                system.out.println(index + "  ");             rowcounter++;             if( rowcounter == 10){                 system.out.println();             }         }     }       }  } 

you should tag question language you're using, i'm gonna assume it's java. problem is

    boolean[] numberisprime = new  boolean[size];     ...     for( int index = 1; index <= size; index++) {          numberisprime[index] = true;     } 

the first line declares numberisprime array of size 10000. means can access numberisprime[0], numberisprime[1], ... numberisprime[9999]. can't access numberisprime[10000].